Business Intelligence (BI) database systems process extremely complex queries upon massive amounts of data. This capability is important to modern enterprises, which rely upon the collection, integration, and analysis of an expanding sea of information. Analysts predict that data warehouses will grow in size and complexity.
BI queries exhibit a significant variance in response times. Most queries are known to execute in under a minute, but some small number of them require hours of execution time. According to conventional wisdom, the presence of even a few poorly written or poorly optimized queries can significantly impact the performance of a data warehouse system by taking up resources that could otherwise be used by properly functioning queries. It is not straightforward to estimate accurately how long a long-running query will take. Although customers may have service level agreements (SLAs) that spell out financial consequences, and although jobs have deadlines, the deadlines are not necessarily explicit or straightforward (or even necessarily possible) to link SLAs to deadlines.
Long running BI queries consume large resources and pose problems for administrators of databases. Administrators are regularly forced to decide which queries are hurting system performance and what action to take against such long running queries.